there's these funny white fibre picks that are 3mm, weird things, they wear/slide rather than flex, so you're not putting 3mm of death straight into your strings. still pretty horrible, but i was having a bitch of a time with RSI at that time.

I used to use .75 tortex ones which were pretty good but one day I read a post and this guy was raving on about them and I thought "3mm....Jesus thats thick" but I grabbed one at the RS oneday and havn't looked back.

I find that instead of digging into the string they 'roll over' it because of the shape of the pick and I get more control because of the rigity, so when Im busting out some palm muted 16ths or fast fills they really come in handy.
I've found it has helped my right hand pick technique out a heap!

I'm a bit slow, just saw this thread. I work for the Dunlop importer/wholesaler and we have Dunlop Primetone picks which come in 3mm and 5mm (!!). You can get them by asking your local music store for them. They probably wont have them in stock, but they can order them from us.
BTW: I'm not normally a pick user, but these things sound great!

I might have to try some fat picks and soft ones and felt ones. I've become a pick player 95% of the time due to my right fingers being a bit RSI'd out and have been using ordinary old celluloid picks with sufficient success. I'm sure there must be a better way out there somewhere.